The process of perming hair consists of two essential steps. The first step is the breaking (reduction) of keratin disulfide (K--S--S--K) bonds in the hair to produce K--S--H functionality. The K--S--H groups are then oxidized in a curled state to produce new crosslinked K--S--S--K bonds. The typical agents for reducing the bonds are thioglycolate salts, which cause the strong odor associated with the perms. The typical agent for the oxidation of the bonds is hydrogen peroxide.
Mercapto-functional siloxanes and their use in the perming process of hair is known in the art. These materials usually contain a reactive --SH functional group on the end of the siloxane chain thereby making them useful substitutes for organic thioglycolates. Of the compounds known in the art the --SH functionality is attached directly on the silicon atom or it is attached to the silicon through an organic linkage consisting of carbon, hydrogen and optionally oxygen.
U.S. Pat. No. 2,944,942 to Charle et al. teaches methylsilyl mercaptoacetates that are useful in the permanent deformation of live hair and other analogous fibers. The --SH is attached to the silicon atom through an acetate linkage. These materials, as taught by Charle et al., are produced by the reaction between a methyl chlorosilane and an excess of an alkali metal thioglycolate. These materials, when used as a reducing agent, help protect and embellish while increasing the elasticity and luster of the hair.
U.S. Pat. No. 3,314,982 to Koerner et al. teaches the preparation of organosilicon compounds containing an alkyl mercapto group on the silicon atom. These compounds are formed through an alkaline cleavage reaction. In this instance the --SH functionality is attached to the silicon atom through an alkyl linkage comprised of at least 3 carbon atoms. Isothiuronium salt compounds, which are formed as an intermediate, are also described. Hair that has been treated with the materials taught by this invention is imparted with a permanent softness and can be easily styled and shaped.
British Patent No. 1,182,939 to Musolf teaches mercapto alkoxysilanes or siloxane polymers which are applied as an aqueous dispersion after the keratin disulfide linkages have been broken and prior to reoxidizing them. The --SH functionality may be directly attached to the silicon atom in this patent or attached through alkyl linkages. These compounds create water repellant properties on the hair as well as sheen and luster. The organosilicon compounds, as taught by Musolf, impart to the hair an improved body and sheen and a water resistant character.
British Patent No. 1,199,776 to McCarty et al. teaches the mercapto polysiloxanes that are chemically bonded into the hair. They are applied after reduction but prior to oxidation of the hair. The polysiloxanes are produced by equilibration reactions or by co-hydrolysis and condensation. The --SH functionality is attached to the silicon atom through an alkyl linkage. These compounds render the hair more attractive and provide a mechanism for protecting the hair against humidity caused effects.
The compounds of the instant invention are novel in that the --SH functionality is joined to the silicon atom through an amide-functional group. The presence of the amide groups and the thio functionality provide unique properties when used in hair waving or straightening.
The objects of this invention are novel thioglycolamide functional siloxanes and their salts and a method for their preparation.
It is also an object of this invention to use the thioglycolamide functional siloxanes in the perming and conditioning of human hair.